1. Field of the Invention
The present invention relates to a foam sheet for a vehicle interior and more particularly relates to a laminated foam sheet to be used for a vehicle interior such as a headliner having superior characteristics in heat resistance and in lightweight.
2. Description of the Prior Art
So far, as vehicle interior materials, a laminated foamed body comprising a thermoplastic resin foamed body as a base material and a urethane foam laminated on the base material, and a laminated foamed body molded in desired shape using a laminated foam sheet comprising a styrene-maleic anhydride resin foamed layer and styrene-maleic anhydride resin film layers laminated on both side of said foamed layer, have been widely used. These vehicle interior materials have superior characteristics in light weight, heat insulation and its moldability.
However, vehicle interior materials currently used for headliners in particular are insufficient in heat resistance, and thus have a defect of hanging down (heat-sagging) by their weight at the front portion of the molded body and also a defect of deformation, when used for a long time at a high temperature.
In order to solve these problems, a composite material comprising inorganic glass fiber and plastics has been used for a vehicle interior material recently.
However, although this composite material can sustain heat resistance, it still has problems that the weight cannot be reduced, the recycling is difficult due to glass fibers contained and the cost is high.
Therefore, a laminated foam sheet for a headliner, which has light weight and heat resistance, has been proposed [JITSUKAI-HEI-4(1992)-11162)(Unexamined Japanese Utility Model Application)]. It comprises modified polyphenylene ether (PPE) resin foamed layer, both sides of which are laminated with modified polyphenylene ether resin film layer. The laminated foam sheet comprising a modified polyphenylene ether resin is superior in heat resistance and light weight, and thus is considered being capable of improving its deformation and hang-down when subjected to a high temperature.
On the other hand, recently the requirements for cars from heat resistance, light weight, and cost have become severe and therefore, further improvements are necessary in order to meet such requirements in the market. For example, the front portion and the rear portion of a car are sometimes heated to 100.degree. C. or so, when exposed to the sun light resulting in a big deformation. Therefore, there still remains a problem in its heat resistance particularly on the front or rear portion thereof with such above mentioned simple laminated foam sheet using modified polyphenylene ether resin.